BIOTEK has discovered a unique processing method for the efficient and safe formulation of peptides or proteins in polylactide-co-glycolide (PLGA) polymer for long-term implantable delivery. The process is very mild, it gives high yield, and residual organic solvent content is very low. BIOTEK has found that certain combinations of solvent and non-solvent liquids can be used to facilitate blending and microlayered implant filling of drug and PLGA particles without the use of heat or high shear in a way never before possible. This mild processing will be especially valuable in formulations containing peptides and proteins. Also, the process has a very high yield, an important factor when the drugs of interest are costly. The development of this method would offer safe and more economical production of therapeutic protein and peptide products. BIOTEK proposes to apply this microlayered implant technology to the development of a long-lasting delivery formulation of the protein erythropoietin. The BIOTEK technology may also be applicable to other therapeutic proteins